Bobbin and loudspeaker using the same

ABSTRACT

A bobbin includes a stratiform composite structure. The stratiform composite structure includes an amorphous carbon structure and a carbon nanotube film structure composited with the amorphous carbon structure. The amorphous carbon structure and the carbon nanotube film structure are combined by van der Waals attractive force and covalent bonds therebetween.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/824,349, filed Jun. 28, 2010, entitled, “BOBBINAND LOUDSPEAKER USING THE SAME,” which claims all benefits accruingunder 35 U.S.C. §119 from China Patent Application No. 200910190570.0,filed on Sep. 30, 2009, in the China Intellectual Property Office.

BACKGROUND

1. Technical Field

The present disclosure relates to bobbins and speakers adopting thesame.

2. Description of Related Art

Among the various types of loudspeakers, electro-dynamic loudspeakersare most widely used because they have simple structures, good soundquality, and low costs. The electro-dynamic loudspeaker typicallyincludes a diaphragm, a bobbin, a voice coil, a damper, a magnet, and aframe. The voice coil is an electrical conductor wrapped around thebobbin. The bobbin is connected to the diaphragm. The voice coil isplaced in the magnetic field of the magnet.

To evaluate the quality of a loudspeaker, sound volume is a decisivefactor. Sound volume of the loudspeaker relates to the input power ofthe electric signals and the conversion efficiency of the energy (e.g.,the conversion efficiency of the electricity to sound). The larger theinput power, the larger the conversion efficiency of the energy; and thebigger the sound volume of the loudspeaker. However, when the inputpower is increased to certain levels, the bobbin and diaphragm coulddeform or even break, thereby causing audible distortion. Therefore, thestrength and tensile modulus of the elements in the loudspeaker aredecisive factors of a rated power of the loudspeaker. The rated power isthe highest input power by which the loudspeaker can produce soundwithout the audible distortion. Additionally, the lighter the weight ofthe elements in the loudspeaker, such as the weight of the bobbin andthe weight per unit area of the diaphragm, the smaller the energyrequired for causing the diaphragm to vibrate, the higher the energyconversion efficiency of the loudspeaker, and the higher the soundvolume produced by the same input power. Thus, the strength, the tensilemodulus, and the weight of the bobbin are important factors affectingthe sound volume of the loudspeaker. The weight of the bobbin is relatedto a thickness and a density thereof. Accordingly, the higher thespecific strength (e.g., strength-to-density ratio), the smaller thethickness of the bobbin of the loudspeaker, and the higher the soundvolume of the loudspeaker.

However, the typical bobbin is usually made of paper, cloth, polymer, orcomposite material. The rated power of the conventional loudspeakers isdifficult to increase partly due to the restriction of the conventionalmaterial of the bobbin. In general, the rated power of a small sizedloudspeaker is only 0.3 watt (W) to 0.5 W. A thicker bobbin has a largerspecific strength, but increases the weight of the bobbin. Thus, it isdifficult to improve the energy conversion efficiency of theloudspeaker. To increase the rated power, the energy conversionefficiency of the loudspeaker, and sound volume, the focus is onincreasing the specific strength and decreasing the weight of thebobbin.

What is needed, therefore, is to provide a bobbin with high specificstrength and light weight, and a loudspeaker using the same.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic structural view of an embodiment of a loudspeaker.

FIG. 2 is a cross-sectional view of the loudspeaker of FIG. 1.

FIG. 3 is a schematic structural view of an embodiment of a bobbin.

FIG. 4 is a magnification of a cross-sectional view of a part of acarbon nanotube composite structure of the bobbin.

FIG. 5 shows a Scanning Electron Microscope (SEM) image of a flocculatedcarbon nanotube film.

FIG. 6 shows an SEM image of a pressed carbon nanotube film.

FIG. 7 shows an SEM image of a drawn carbon nanotube film.

FIG. 8 shows an SEM image of a carbon nanotube film structure consistingof a plurality of stacked drawn carbon nanotube films.

FIG. 9 is a flowchart of the method for making the stratiform compositestructure according to one embodiment.

FIG. 10 is a flowchart of the method for making the stratiform compositestructure according to another embodiment.

FIG. 11 is a schematic structural view of an embodiment of aloudspeaker.

FIG. 12 shows an SEM image of an untwisted carbon nanotube wire.

FIG. 13 shows an SEM image of a twisted carbon nanotube wire.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Referring to FIG. 1 and FIG. 2, one embodiment of a loudspeaker 100 isshown. The loudspeaker 100 includes a frame 110, a magnetic circuit 120,a voice coil 130, a bobbin 140, a diaphragm 150 and a damper 160.

The frame 110 can be mounted on an upper side of the magnetic circuit120. The voice coil 130 can be received in the magnetic circuit 120 andwind around the voice coil bobbin 140. An outer rim of the diaphragm 150can be fixed to an inner rim of the frame 110, and an inner rim of thediaphragm 150 can be fixed to an outer rim of the bobbin 140 placed inthe magnetic circuit 120.

The frame 110 can be a truncated cone with an opening on one end andincludes a hollow cavity 111 and a bottom 112. The hollow cavity 111 canreceive the diaphragm 150 and the damper 160. The bottom 112 can have acenter hole 113. The center pole 124 can be extended through the centerhole 113. The bottom 112 of the frame 110 can be fixed to the magneticcircuit 120.

The magnetic circuit 120 can include a lower plate 121, an upper plate122, a magnet 123, and a center pole 124. The magnet 123 can besandwiched by the lower plate 121 and the upper plate 122. The upperplate 122 and the magnet 123 can be circular, and define a substantiallycylindrical shaped space in the magnetic circuit 120. The center pole124 can be received in the substantially cylindrical shaped space andextend through the center hole 113. The center pole 124 can extend fromthe lower plate 121 to the upper plate 122 to define a magnetic gap 125with the magnet 123. The magnetic circuit 120 can be fixed on the bottom112 via the upper plate 122. The upper plate 122 can be fixed on thebottom 112 via adhesive or mechanical force. In one embodiment,according to FIG. 1, the upper plate 122 is fixed on the bottom 112 byscrews (not shown).

The voice coil 130 wound on the bobbin 140 can be a driving member ofthe loudspeaker 100. The voice coil 130 can be made of conducting wire.When the electric signals are input into the voice coil 130, thevariation of the electric signals can form a magnetic field. Theinteraction of the magnetic field caused by the voice coil 130 and themagnetic circuit 120 can produce the vibration of the voice coil 130.The vibration of the voice coil 130 causes the voice coil bobbin 140 tovibrate, which in turn, causes the diaphragm 150 fixed on the voice coilbobbin 140 to vibrate. The vibration of the diaphragm 150 causes theloudspeaker 100 to produce sound.

The diaphragm 150 is a sound producing member of the loudspeaker 100.The diaphragm 150 can have a conical shape if used in a large sizedloudspeaker 100. If the loudspeaker 100 has a smaller size, thediaphragm 150 can have a planar circular shape or a planar rectangularshape. In one embodiment according to FIG. 1, the diaphragm 150 has aconical shape.

The damper 160 has a through hole therein to define an inner rim 161.The inner rim 161 of the damper 160 can be fixed to the bobbin 140. Anouter rim of the damper 160 can be fixed to the frame 110. Thus, thedamper 160 can mechanically hold the diaphragm 150 connected to thebobbin 140. The damper 160 can be a substantially ring-shaped platehaving radially alternating circular ridges and circular furrows.Simultaneously, the damper 160 can include a plurality of concentricrings. The ridges and the furrows can be saw tooth shaped, wave shaped,involute shaped, or combinations thereof. In one embodiment, the ridgesand the furrows are involute shaped. The damper 160 can be formed bymeans of hot pressing. The damper 160 can have a thickness of about 1micrometer to about 1 millimeter.

A plurality of conductive wires (not shown) can be disposed on thedamper 160. The connective wires can be fixed on the damper 160 viaadhesive or mechanical force. The conductive wires electrically connectthe voice coil 130 to a power source.

Referring to FIG. 3, the bobbin 140 can be a hollow tubular structurehaving a through hole 141 therein. The center pole 124 can be disposedin the through hole 141 and spaced from the bobbin 140. When the voicecoil 130 vibrates, the bobbin 140 and the diaphragm 150 also vibratewith the voice coil 130 to produce sound.

Referring to FIG. 3 and FIG. 4, the bobbin 140 can include a carbonnanotube film structure 142 and an amorphous carbon structure 143composited with the carbon nanotube film structure 142 to form astratiform composite structure. A cylindrical configuration can beformed by the stratiform composite structure.

The carbon nanotube film structure 142 defines a plurality of micropores1421. The carbon nanotube film structure 142 is capable of forming afree-standing structure. The term “free-standing structure” can bedefined as a structure that does not have to be supported by asubstrate. For example, a free-standing structure can sustain the weightof itself when it is hoisted by a portion thereof without anysignificant damage to its structural integrity. The free-standingstructure of the carbon nanotube film structure 142 is realized by thecarbon nanotubes joined by van der Waals attractive force. So, if thecarbon nanotube film structure 142 is placed between two separatesupporters, a portion of the carbon nanotube film structure 142 not incontact with the two supporters, would be suspended between the twosupporters and yet maintain film structural integrity.

The carbon nanotube film structure 142 includes a plurality of carbonnanotubes uniformly distributed therein, and joined by van der Waalsattractive force therebetween. The carbon nanotubes in the carbonnanotube film structure 142 can be orderly or disorderly arranged. Theterm ‘disordered carbon nanotube film structure’ includes, but is notlimited to, a structure where the carbon nanotubes are arranged alongmany different directions, such that the number of the carbon nanotubesarranged along each different direction can be almost the same (e.g.uniformly disordered), and/or entangled with each other. ‘Ordered carbonnanotube film structure’ includes, but is not limited to, a structurewhere the carbon nanotubes are arranged in a consistently systematicmanner, e.g., the carbon nanotubes are arranged approximately along asame direction and or have two or more sections within each of which thecarbon nanotubes are arranged approximately along a same direction(different sections can have different directions). The carbon nanotubesin the carbon nanotube film structure 142 can be single-walled,double-walled, and/or multi-walled carbon nanotubes.

Macroscopically, the carbon nanotube film structure 142 may have asubstantially planar structure. The planar carbon nanotube structure canhave a thickness of about 0.5 nanometers to about 100 microns. Thecarbon nanotube film structure 142 includes a plurality of carbonnanotubes and defines a plurality of micropores 1421 having a size ofabout 1 nanometer to about 10 micrometers. The carbon nanotube filmstructure 142 includes at least one carbon nanotube film, the at leastone carbon nanotube film includes a plurality of carbon nanotubessubstantially parallel to a surface of the corresponding carbon nanotubefilm.

The carbon nanotube film structure 142 can include a flocculated carbonnanotube film as shown in FIG. 5. The flocculated carbon nanotube filmcan include a plurality of long, curved, disordered carbon nanotubesentangled with each other and can form a free-standing structure.Further, the flocculated carbon nanotube film can be isotropic. Thecarbon nanotubes can be substantially uniformly dispersed in the carbonnanotube film. The adjacent carbon nanotubes are acted upon by the vander Waals attractive force therebetween, thereby forming an entangledstructure with micropores 1421 defined therein. Alternatively, theflocculated carbon nanotube film is very porous. Sizes of the micropores1421 can be about 1 nanometer to about 10 micrometers. Further, due tothe carbon nanotubes in the carbon nanotube structure being entangledwith each other, the carbon nanotube film structure 142 employing theflocculated carbon nanotube film has excellent durability, and can befashioned into desired shapes with a low risk to the integrity of carbonnanotube structure. The flocculated carbon nanotube film, in someembodiments, will not require the use of structural support or due tothe carbon nanotubes being entangled and adhered together by van derWaals attractive force therebetween. The flocculated carbon nanotubefilm can have a thickness of about 0.5 nanometers to about 100 microns.

The carbon nanotube film structure 142 can include a pressed carbonnanotube film. The carbon nanotubes in the pressed carbon nanotube filmcan be arranged along a same direction or arranged along differentdirections. The carbon nanotubes in the pressed carbon nanotube film canrest upon each other. The adjacent carbon nanotubes are combined andattracted to each other by van der Waals attractive force, and can forma free-standing structure. An angle between a primary alignmentdirection of the carbon nanotubes and a surface of the pressed carbonnanotube film can be in a range from approximately 0 degrees toapproximately 15 degrees. The pressed carbon nanotube film can be formedby pressing a carbon nanotube array. The angle is closely related to thepressure applied to the carbon nanotube array. The greater the pressure,the smaller the angle. The carbon nanotubes in the carbon nanotube filmcan be substantially parallel to the surface of the carbon nanotube filmif the angle is about 0 degrees. A length and a width of the carbonnanotube film can be set as desired. The pressed carbon nanotube filmcan include a plurality of carbon nanotubes substantially aligned alongone or more directions. The pressed carbon nanotube film can be obtainedby pressing the carbon nanotube array with a pressure head.Alternatively, the shape of the pressure head and the pressing directioncan determine the direction of the carbon nanotubes arranged therein.Specifically, in one embodiment, a planar pressure head is used to pressthe carbon nanotube array along the direction substantiallyperpendicular to a substrate. A plurality of carbon nanotubes pressed bythe planar pressure head may be sloped in many directions. In anotherembodiment, as shown in FIG. 6, if a roller-shaped pressure head is usedto press the carbon nanotube array along a certain direction, a pressedcarbon nanotube film having a plurality of carbon nanotubessubstantially aligned along a certain direction can be obtained. Inanother embodiment, if the roller-shaped pressure head is used to pressthe carbon nanotube array along different directions, a pressed carbonnanotube film having a plurality of carbon nanotubes substantiallyaligned along different directions can be obtained. The pressed carbonnanotube film can have a thickness of about 0.5 nanometers to about 100microns, and can define a plurality of micropores 1421 having a diameterof about 1 nanometer to about 10 micrometers.

In some embodiments, the carbon nanotube film structure 142 includes atleast one drawn carbon nanotube film as shown in FIG. 7. The drawncarbon nanotube film can have a thickness of about 0.5 nanometers toabout 100 microns. The drawn carbon nanotube film includes a pluralityof carbon nanotubes that can be arranged substantially parallel to asurface of the drawn carbon nanotube film. A plurality of micropores1421 having a size of about 1 nanometer to about 10 micrometers can bedefined by the carbon nanotubes. A large number of the carbon nanotubesin the drawn carbon nanotube film can be oriented along a preferredorientation, meaning that a large number of the carbon nanotubes in thedrawn carbon nanotube film are arranged substantially along the samedirection. An end of one carbon nanotube is joined to another end of anadjacent carbon nanotube arranged substantially along the samedirection, by van der Waals attractive force. More specifically, thedrawn carbon nanotube film includes a plurality of successively orientedcarbon nanotube segments joined end-to-end by van der Waals attractiveforce therebetween. Each carbon nanotube segment includes a plurality ofcarbon nanotubes substantially parallel to each other, and joined by vander Waals attractive force therebetween. The carbon nanotube segmentscan vary in width, thickness, uniformity and shape. A small number ofthe carbon nanotubes are randomly arranged in the drawn carbon nanotubefilm, and has a small, if not negligible, effect on the larger number ofthe carbon nanotubes in the drawn carbon nanotube film arrangedsubstantially along the same direction. The carbon nanotube film iscapable of forming a free-standing structure.

Understandably, some variation can occur in the orientation of thecarbon nanotubes in the drawn carbon nanotube film as can be seen inFIG. 7. Microscopically, the carbon nanotubes oriented substantiallyalong the same direction may not be perfectly aligned in a straightline, and some curve portions may exist. Furthermore, it can beunderstood that some carbon nanotubes located substantially side by sideand oriented along the same direction and in our contact with eachother.

Referring to FIG. 8, in one embodiment, the carbon nanotube filmstructure 142 includes a plurality of stacked drawn carbon nanotubefilms. The number of the layers of the drawn carbon nanotube films isnot limited. Adjacent drawn carbon nanotube films can be adhered by onlyvan der Waals attractive forces therebetween. An angle can exist betweenthe carbon nanotubes in adjacent drawn carbon nanotube films. The anglebetween the aligned directions of the adjacent drawn carbon nanotubefilms can range from about 0 degrees to about 90 degrees. In oneembodiment, the angle between the aligned directions of the adjacentdrawn carbon nanotube films is about 90 degrees, thus a plurality ofsubstantially uniform micropores 1421 are defined by the carbon nanotubefilm structure 142.

If the carbon nanotubes of the carbon nanotube film structure 142 arealigned along one direction or some predetermined directions, a higherspecific strength can be achieved along the direction of the carbonnanotubes in the carbon nanotube film structure 142. Therefore, byarranging the carbon nanotube film structure 142 to set the carbonnanotubes therein aligned along a particular direction, the specificstrength of the bobbin 140 along this direction can be improved.

The amorphous carbon structure 143 can be infiltrated into themicropores 1421. “Amorphous carbon” is an allotrope of carbon that doesnot have any crystalline structure. The amorphous carbon has nolong-range crystalline order therein. A short-range order can exist, butwith deviations of the interatomic distances and/or inner-bonding angleswith respect to a graphite lattice as well as to a diamond lattice. Theamorphous carbon structure 143 can include a plurality of amorphouscarbon particles 1431 in the micropores 1421. The amorphous carbonparticles 1431 can be combined by covalent bonds therebetween. Theamorphous carbon particles 1431 can be adhered to the carbon nanotubes.The amorphous carbon particles 1431 can also enwrap the carbon nanotubestherein, thus, the carbon nanotubes can be encapsulated in the amorphouscarbon particles 1431. The amorphous carbon particles 1431 and thecarbon nanotubes can be combined by Van der Waals attractive forces andcovalent bonds therebetween. The covalent bonds can be an sp² hybridizedbond or an sp³ hybridized bond between carbon atoms. A plurality ofamorphous carbon particles 1431 can also be disposed on oppositesurfaces of the carbon nanotube film structure 142 to form two amorphouscarbon layers. Thus, the amorphous carbon structure 143 can enwrap thecarbon nanotube film structure 142. A cavernous shaped structure can beformed by the amorphous carbon structure 143. The carbon nanotube filmstructure 142 can be embedded in the cavernous structure.

The amorphous carbon structure 143 can be obtained by carbonizing apolymer, such as polyacrylonitrile fiber, asphalt fiber, viscose fiber,or phenolic fiber, at a carbonization temperature. If the polymer iscarbonized in a vacuum or with inert gases, the carbonizationtemperature can be lower than or equal to 1000° C. If the polymer iscarbonized in normal atmosphere, the carbonization temperature can belower than or equal to 500° C. to prevent the carbon nanotubes frombeing oxidated.

Referring to FIG. 9, in one embodiment, the stratiform compositestructure can be formed by the following steps: S10, dipping the carbonnanotube film structure 142 in a solution with a polymer dissolvedtherein; and S20, carbonizing the carbon nanotube film structure 142infiltrated in the polymer.

In step S10, the polymer and the carbon nanotube film structure 142 canbe combined together by Van der Waals attractive forces and covalentbonds therebetween. In step S20, the polymer can be carbonized toamorphous carbon particles 1431 combined by covalent bonds therebetween.

Referring to FIG. 10, in one embodiment, the stratiform compositestructure can be formed by the following steps:

-   -   S110, dipping the carbon nanotube film structure 142 in a        solution, wherein a pre-polymer is dissolved in the solution;    -   S120, polymerizing the pre-polymer solution into a polymer; and    -   S130, carbonizing the carbon nanotube film structure 142 with        the polymer infiltrated therein.

In step S110, the pre-polymer can be acrylonitrile, ethyl acrylate,butyl acrylate, styrene, butadiene, or combinations thereof.

Both the carbon nanotubes of the carbon nanotube film structure 142 andthe amorphous carbon particles 1431 of the amorphous carbon structure143 are carbon materials. Thus, a density of the bobbin 140 can besmaller, and accordingly, a weight of the bobbin 140 can be lighter. Ahigher energy conversion efficiency of the loudspeaker 100 can beobtained. The carbon nanotubes and the amorphous carbon particles 1431are combined by the covalent bonds therebetween. A stress and atensility formed by the bobbin 140 can be borne by most of the carbonnanotubes and the amorphous carbon particles 1431, when the bobbin 140moves up and down with the diaphragm 150. Thus, a higher specificstrength of the bobbin 140 can be achieved. A higher volume of theloudspeaker 100 can be obtained.

Referring to FIG. 11, another embodiment of a loudspeaker 200 is shown.The loudspeaker 200 can include a frame 210, a magnetic circuit 220, avoice coil 230, a bobbin 240, a diaphragm 250, and a damper 260.

The frame 210 can be mounted on an upper side of the magnetic circuit220. The voice coil 230 can be received in the magnetic circuit 220. Thevoice coil 230 can wind around the voice coil bobbin 240. An outer rimof the diaphragm 250 can be fixed to an inner rim of the frame 210, andan inner rim of the diaphragm 250 can be fixed to an outer rim of thebobbin 240 placed in the magnetic circuit 220. The bobbin 240 includes acarbon nanotube film structure and an amorphous carbon structurecomposited with the carbon nanotube film structure to form a stratiformcomposite structure. The magnetic circuit 220 includes a lower plate221, an upper plate 222, a magnet 223, and a center pole 224. The magnet223 is sandwiched by the lower plate 221 and the upper plate 222. Theupper plate 222 and the magnet 223 are circular, and define asubstantially cylindrical shaped space in the magnetic circuit 220. Thecenter pole 224 extends from the lower plate 221 to the upper plate 222to define a magnetic gap 225 with the magnet 223.

The compositions, features, and functions of the loudspeaker 200 in theembodiment shown in FIG. 11 are similar to the loudspeaker 100 in theembodiment shown in FIG. 1, except that the carbon nanotube filmstructure can include at least one carbon nanotube wire structure. Theat least one carbon nanotube wire structure can include a plurality ofcarbon nanotubes joined end to end by van der Waals attractive forcetherebetween along an axial direction. The at least one carbon nanotubewire structure includes one or more carbon nanotube wires substantiallyparallel to each other to form a bundle-like structure or twisted witheach other to form a twisted structure. The bundle-like structure andthe twisted structure are two kinds of linear shaped carbon nanotubestructures. The plurality of carbon nanotube wire structures can bewoven together to form a planar shaped carbon nanotube structure.

The carbon nanotube wire can be untwisted or twisted. Treating the drawncarbon nanotube film with a volatile organic solvent can obtain theuntwisted carbon nanotube wire. In one embodiment, the organic solventcan be applied to soak the entire surface of the drawn carbon nanotubefilm. During the soaking, adjacent substantially parallel carbonnanotubes in the drawn carbon nanotube film will bundle together, due tothe surface tension of the organic solvent as it volatilizes, and thus,the drawn carbon nanotube film will be shrunk into an untwisted carbonnanotube wire. The untwisted carbon nanotube wire includes a pluralityof carbon nanotubes substantially oriented along a same direction (i.e.,a direction along the length direction of the untwisted carbon nanotubewire) as shown in FIG. 12. The carbon nanotubes are substantiallyparallel to the axis of the untwisted carbon nanotube wire. In oneembodiment, the untwisted carbon nanotube wire includes a plurality ofsuccessive carbon nanotubes joined end to end by van der Waalsattractive force therebetween. The length of the untwisted carbonnanotube wire can be arbitrarily set as desired. A diameter of theuntwisted carbon nanotube wire ranges from about 0.5 nm to about 100 μm.

The twisted carbon nanotube wire can be obtained by twisting a drawncarbon nanotube film using a mechanical force to turn the two ends ofthe drawn carbon nanotube film in opposite directions. The twistedcarbon nanotube wire includes a plurality of carbon nanotubes helicallyoriented around an axial direction of the twisted carbon nanotube wireas shown in FIG. 13. In one embodiment, the twisted carbon nanotube wireincludes a plurality of successive carbon nanotubes joined end to end byvan der Waals attractive force therebetween. The length of the carbonnanotube wire can be set as desired. A diameter of the twisted carbonnanotube wire can be about 0.5 nm to about 100 μm.

The carbon nanotube wire can be a free-standing structure. The lengthdirection of the carbon nanotube wire can have a high specific strength.Therefore, by arranging the carbon nanotube wire to set the carbonnanotube wire aligned substantially along a particular direction, thespecific strength of the bobbin 240 along this direction can beimproved.

It is to be understood that the above-described embodiments are intendedto illustrate rather than limit the present disclosure. Any elementsdescribed in accordance with any embodiments is understood that they canbe used in addition or substituted in other embodiments. Embodiments canalso be used together. Variations may be made to the embodiments withoutdeparting from the spirit of the disclosure. The above-describedembodiments illustrate the scope, but do not restrict the scope of thedisclosure.

What is claimed is:
 1. A bobbin comprising: a stratiform compositestructure comprising an amorphous carbon structure and a carbon nanotubefilm structure composited with the amorphous carbon structure; whereinthe carbon nanotube film structure is a free-standing structure, theamorphous carbon structure and the carbon nanotube film structure arecombined by van der Waals attractive force and covalent bondstherebetween.
 2. The bobbin as claimed in claim 1, wherein the carbonnanotube film structure is enwrapped by the amorphous carbon structure.3. The bobbin as claimed in claim 1, wherein the stratiform compositestructure has a hollow tubular structure.
 4. The bobbin as claimed inclaim 3, wherein the hollow tubular structure comprises two amorphouscarbon structures, and the carbon nanotube film structure is sandwichedbetween the two amorphous carbon structures.
 5. The bobbin as claimed inclaim 1, wherein the carbon nanotube film structure comprises aplurality of carbon nanotubes.
 6. The bobbin as claimed in claim 5,wherein the plurality of carbon nanotubes are joined end to end by vander Waals attractive force therebetween.
 7. The bobbin as claimed inclaim 1, wherein the amorphous carbon structure comprises a plurality ofamorphous carbon particles.
 8. The bobbin as claimed in claim 7, whereinthe carbon nanotube film structure comprises a plurality of carbonnanotubes and the plurality amorphous carbon particles adhere to theplurality of carbon nanotubes or enwrap the plurality of carbonnanotubes.
 9. The bobbin as claimed in claim 7, wherein the plurality ofamorphous carbon particles are combined together by covalent bondstherebetween.
 10. The bobbin as claimed in claim 9, wherein the covalentbonds comprises an sp² hybridized bond or an sp³ hybridized bond betweencarbon atoms.
 11. The bobbin as claimed in claim 1, wherein the carbonnanotube film structure comprises a carbon nanotube film or a pluralityof carbon nanotube films stacked together or coplanarly arranged, andthe carbon nanotube film comprises a plurality of carbon nanotubes. 12.The bobbin as claimed in claim 11, wherein the carbon nanotube film isisotropic and the plurality of carbon nanotubes therein are entangledwith each other.
 13. The bobbin as claimed in claim 11, wherein theplurality of carbon nanotubes are substantially parallel to a surface ofthe carbon nanotube film.
 14. The bobbin as claimed in claim 11, whereinthe plurality of carbon nanotubes are substantially aligned in a singledirection and joined end to end by van der Waals attractive forcetherebetween.
 15. The bobbin as claimed in claim 1, wherein the carbonnanotube film structure comprises a carbon nanotube wire structurecomprising at least one carbon nanotube wire comprising a plurality ofcarbon nanotubes joined end to end by van der Waals attractive forcetherebetween along an axial direction.
 16. The bobbin as claimed inclaim 1, wherein the carbon nanotube film structure comprises aplurality of carbon nanotube wire structures substantially parallel toeach other, crossed with each other, or woven together.
 17. The bobbinas claimed in claim 1, wherein the amorphous carbon structure is acavernous shaped structure, and the carbon nanotube film structure isembedded in the cavernous shaped structure.
 18. The bobbin as claimed inclaim 1, wherein the carbon nanotube film structure comprises aplurality of ring-shaped carbon nanotube wire structures separatelyarranged in the amorphous carbon structure.
 19. A loudspeaker comprisinga frame; a magnetic circuit defining a magnetic gap, the magneticcircuit being mounted on the frame; a damper received in the frame; anda bobbin located in the magnetic gap and engaging with the damper;wherein the bobbin comprises a stratiform composite structure comprisingan amorphous carbon structure and a carbon nanotube film structurecomposited with the amorphous carbon structure; wherein the amorphouscarbon structure and the carbon nanotube film structure are combined byvan der Waals attractive force and covalent bonds therebetween.
 20. Theloudspeaker as claimed in claim 19, wherein the stratiform compositestructure has a hollow tubular structure comprising two amorphous carbonstructures, and the carbon nanotube film structure is sandwiched betweenthe two amorphous carbon structures.